Slide for the microscopic examination of biological fluids

ABSTRACT

The slide for the microscopic examination of biological fluids is constituted by two plates of transparent material, one plate being the bottom and the other plate being the cover, the plates forming wells which are filled by capillarity with the biological fluid to be examined. The reliefs which define each computation chamber sectioned along a plane perpendicular to the bottom of the well have a shaped section along a profile assimilable to a polygon having at least one right angle.

FIELD OF THE INVENTION

[0001] This invention relates to slides for the microscopic examination of biological fluids, according to the general part of claim 1.

BACKGROUND OF THE PRIOR ART

[0002] It is well known that for the microscopic examination of biological fluids such as urine, blood, spinal fluids, for the purpose of carrying out a computation of the elements present in a predefined sample, have been used plates, called slides, constituted by two plates of transparent plastic material, one for the floor and one for the covering which define in their interior a plurality of wells, which are filled by capillarity with drops of the biological fluid which is deposited on the slide itself,

[0003] On the floor of each well are formed computation chambers, in each of which is contained an accurate volume of the biological fluid to be examined. These computation chambers are obtained by means of reliefs which are formed from the floor of the well towards the roof.

[0004] In reference to the trajectory of the reliefs it is possible to obtain quadrilateral or circular computation chambers, depending whether the reliefs have a rectilinear direction so as to form grids or have a circular direction so as to form circles which are reciprocally separated. By way of example of the first type of computation chamber there is mentioned the European patent No. 326349 which describes a slide made of plastic material in which the computation chambers in a well are defined by reliefs obtained with symmetrical lines which have a width of between about 0.005 mm and 0.05 mm and which extend upwardly from the floor of the well preferably for 0.008 mm and the minimal area for the reading of each chamber has a surface of 0.111 square mm (mm²).

[0005] Also by way of example, with respect to the second type of computation chamber the slides produced by the company Kima have reliefs of width between 0.005 mm and 0.05 mm and the reliefs form a circular computation chamber having as the floor a circle of internal diameter 0.376 mm.

[0006] Usually the reliefs, grids or circular, define computation chambers, preferably arranged 3×3, the total internal surface of all the chambers being 1 mm^(2.)

[0007] The production by exposure to a press of these types of slides made of plastic material requires, in order to obtain reliefs of millesimal dimensions the use of moulds provided with engraved marks and impressions which are of microscopic value, well defined, and which are made only by means of special machines for the removal of chips, by electroerosion or with other particular working processes, known in the present state of the art.

SUMMARY OF THE INVENTION

[0008] The object of the present invention is to provide slides in which the computation chambers present in one or more wells, are defined by reliefs which protrude from the bottom, which are preferably rectilinear or circular, which have a profile easily achievable with machines and which however define precise lateral walls of the computation chamber so as to ensure accurately the volume of the chamber. In fact, by means of the constructive known up to the present, the observation with the optical microscope for measuring the small particles can never be accurate because in the observed reliefs the optical lines which correspond respectively to the line of the vertex and to the line of the bottom of the relief, are subject to confusion due to the inclination of the wall of the relief.

[0009] This fact causes an error in the reading or in the computation of the small particles because it is not possible to examine the small particles which remain adhering to the inclined walls and there is a different value of the area of reading when it is measured on the upper plane which corresponds and it is defined by the vertex of the relief and when it is measured at the bottom of the computation chamber. This error is further increased due to the fact that it is impossible to provide reliefs with inclined walls which are perfectly uniform along the entire computation chamber.

[0010] The object of the invention is achieved by providing reliefs which dissected along a plane perpendicular to the bottom of the well, have a section shaped along a profile assimilable to a polygon having at least one right angle and in which one of the two sides which define this right angle constitutes the internal lateral wall of the computation chamber in a manner that also the angle defined by the bottom of the chamber and the lateral wall is also a right angle.

[0011] The invention further provides that the lateral wall of the computation chamber has its upper extremity constituted by a corner which is part of the polygon which defines the relief, and which has an internal angular opening of 90 degrees at the most and the apex is rounded up to a curvature ray at the most 0.002 mm.

[0012] In operation, the preferred form of the reliefs is a rectangular trapezium or a rectangular triangle, embodiments which essentially better define the separation between the area which constitutes the computation chamber and the surrounding area which separates reciprocally the plurality of the chambers.

[0013] The characteristics of the invention will be better clarified by reference to a description of a possible embodiment provided by way of illustration of a non-limiting example, as described in the figures, of which:

[0014]FIG. 1 shows a perspective view of the entire slide according to the present invention;

[0015]FIG. 2 shows a matrix of nine computation chambers, disposed 3×3;

[0016] FIGS. 3A-3B-3C show respectively a plan view, a cross-sectional view according to line III-III and a detailed view of a computation chamber defined by a relief having a section in the shape of a rectangular trapezium;

[0017]FIGS. 4A, 4B, 4C show respectively a plan view, a cross-sectional view according to line IV-IV and a detailed view of a computation chamber defined by a relief having a section in the shape of a rectangular triangle;

[0018]FIG. 5 shows a detailed view of the upper extremity of the wall of the computation chamber.

[0019] As shown in FIG. 1, the slide (1) made of plastic material is made of a lower plate (2) which is assembled preferably by soldering with ultrasound with upper plate (3). These two plates after they are assembled, define wells (4) which are constituted by floor (5) which is part of the lower plate perfectly planar and smooth, with a grade of roughness which should be the lowest possible and roof (6) with such characteristics of transparency to provide optimal microscopic observation.

[0020] Each well is filled with a drop of the sample of biological fluid which is deposited on the threshold (8) which is formed on the lower plate and which penetrates by capillarity through opening (9). In the described configuration each well has an area of about 66 mm² and contains a volume equal to 6.6 mm³.

[0021] At the bottom of each well (4) is present a matrix (10) constituted by nine chambers of computation (11) disposed in series of 3×3. Each chamber of computation (11) is constituted by a circle of internal diameter 0.376 mm. The chamber is limited by a relief (12). Each relief is characterized by the fact that it has a section of a rectangular trapezium as shown in FIG. 3 or a rectangular triangle as shown in FIG. 4 in which the side of the right angle constitutes the internal vertical wall (13) of the chamber.

[0022] Finally, as shown in FIG. 5, the upper extremity of the wall (13) is rounded with a ray at the most of 0.002 mm.

[0023] Obviously some embodiments different from the embodiment which has been described, in form, dimensions and the number of the wells and of the cells of computation present in each well or in the use of material which is not plastic as glass but technically equivalent and contingent to use are possible, but still within the scope of the attached claims. 

What is claimed is: 1) A slide for the microscopic examination of biological fluids such as urine, blood, spinal fluids for the purpose of carrying out a computation of the elements in a predefined sample, said slide comprising first and second plates of transparent material, said first plate forming the floor and said second plate forming the covering, said plates forming in the interior at least one well, said well being filled by capillarity with the drops of said biological fluid which is deposited on said slide, computation chambers being formed on the bottom of said well, said computation chambers being reliefs, said reliefs extending from the bottom of the well, each chamber enclosing a precise volume of said biological fluid being examined, said reliefs defining each computation chamber sectioned along a plane perpendicular to the bottom of said well have a section shaped along a profile assimilable to a polygon which has at least one right angle and wherein one of the two sides which define said right angle comprises the internal lateral wall of the computation chamber in a manner that the angle defined by the floor of the chamber and by the lateral wall also is a right angle. 2) The slide according to claim 1, wherein the lateral wall of said computation chamber has its upper extremities constituted by a corner which is part of said polygon which defines said relief, said polygon having an internal angular opening which is at the most 90 degrees and the cuspid is rounded up to a radius of curvature at the most 0.002 mm. 3) The slide according to claim 1, wherein the reliefs extend rectilinearly whereby the computation chambers have a quadrilateral shape. 4) The slide according to claim 1, wherein the reliefs extend circularly whereby the computation chambers are constituted by circles. 5) The slide according to claim 1, wherein the relief has a section with a profile in the shape of a rectangular trapezium. 6) The slide according to claim 1, wherein the relief has a section with a profile in the shape of a right triangle. 7) A slide for the microscopic examination of biological fluids comprising a lower plate (2) and an upper plate (3) said two plates after they are assembled reciprocally, for instance by soldering with ultrasound, provide to define wells (4), said wells comprising a bottom (5) which is part of the lower plate and is plane and smooth with the lowest possible roughness and a roof (6) with a transparency property capable of permitting optical microscopic observation, each well adapted to being filled with a drop of sample of the biological fluid which is deposited on a threshold (8) formed on the lower plate, said drop penetrating by capillarity through an opening (9) to the bottom of each well and a matrix (10) being present on the bottom of each well, said matrix being constituted by nine computation chambers (11) arranged in 3×3 series, the slide being further characterized by the fact that each computation chamber (11) is delimited by a circular relief (12). 8) The slide according to claim 7, wherein said relief (12) has a section with the profile of a rectangular trapezium in which the side of the right angle constitutes the internal vertical wall (13) of the computation chamber (11). 9) The slide according to claim 7, wherein the relief (12) has a section with the profile of a right triangle in which the side of the right angle constitutes the internal vertical wall (13) of the computation chamber (11). 10) The slide according to claim 8, wherein the extremity of the internal vertical wall (13) is rounded with a radius of curvature of at the most 0.002 mm. 11) The slide according to claim 9, wherein the extremity of the internal vertical wall (13) is rounded with a radius of curvature of at most 0.002 mm. 